140 CLASS MAMMALIA. 



according to the order of their common relations, than to 

 procure the means of determining the species with more 

 rigorous precision. It was unfortunate that this sacrifice 

 made to the advantages of a good classification, failed even 

 to produce its intended effect, inasmuch as the observations 

 relative to the number of incisors which are quoted in these 

 writers are for the most part incorrect. 



The result then, in fact, proved to be neither a good 

 classification for the families, nor an exact method for 

 arriving at the determination of the species. The disorder 

 which reigned on those points in later systematic works, is 

 sufficiently proved by the difficulty, if not, indeed, impossi- 

 bility, of employing the characters given in such works for 

 the purpose of recognising the living objects themselves. 



Under such circumstances it was absolutely necessary to 

 revise in some degree the labours of preceding naturalists 

 on the subject of the bats. This task has been undertaken 

 and most admirably performed by M. Geoffroy St. Hilaire, 

 to whom we owe the substance of most of our observations 

 on the cheiroptera. He set out upon the principle, that the 

 cheiropterous tribes admitted of subdivisions perfectly in 

 conformity to nature, and he has particularly succeeded in 

 re-establishing the genus vespertilio, such as it was formed 

 by Brisson, in explaining and enforcing the grounds on which 

 it rests, and describing the species of which it is composed. 



These bats, which comprise nearly all the cheiroptera 

 found in Europe are remarkable for the largeness of their 

 head, their short muzzle, naked ears, and the existence of 

 an auricula or tragus, which originates from the centre of 

 the auricular conch ; for nostrils without membrane or ap- 

 pendage ; and for a very long tail. They are capable of a 

 very permanent and extensive flight, comprising within the 

 two extremities of the wings a length four or five times as 

 great as that of the body. The surface of their wings is 

 moreover materially augmented by the interfemoral mem- 



